Process for producing styrenic polymer

Abstract

There is disclosed a process for producing a syndiotactic polystyrene (SPS) which comprises polymerizing a styrenic monomer having a content of indene-based compounds of at most 50 ppm by bringing a polymerization catalyst into contact with the above styrenic monomer, which catalyst preferably comprises an (A) transition metal compound (e.g. Ti compound) and (B) an (a) compound capable of reacting with the above transition metal compound (component (A)) to form an ionic complex (e.g. DMAB) or a (b) oxygen atom-containing compound (e.g. MAO), and optionally a (C) alkyl group-containing metallic compound (e.g. TIBA). By virtue of using the above styrenic monomer, the process enables to minimize the amount of the residual metals in the resultant styrenic polymer without deterioration of the catalytic activity, simplify the process and thereby curtail the production cost of SPS.

What is claimed is: 
     
       1. A process for producing a styrenic polymer having a syndiotactic configuration which comprises polymerizing a styrenic monomer having a content of indene-based compounds of at most 50 ppm by bringing a polymerization catalyst for producing the styrenic polymer having a syndiotactic configuration into contact with said styrenic monomer. 
     
     
       2. The process according to claim 1 wherein said polymerization catalyst comprises an (A) transition metal compound and (B) at least one compound selected from the group consisting of an (a) compound capable of reacting with said transition metal compound as the component (A) to form an ionic complex and a (b) oxygen atom-containing compound represented by the formula (I) or by the formula (II) ##STR11## wherein Z is a structure in which one or more groups represented by the formula ##STR12## are arranged in an arbitrary order in the number of arbitrary positive integers; R 1  to R 9  are each an alkyl group having 1 to 8 carbon atoms and may be the same as or different from each other; y 1  and y 3  are each a Group 13 metal of the Periodic Table and may be the same as or different from each other; and y 2  and y 4  are each a Group 14 metal of the Periodic Table and may be the same as or different from each other. 
     
     
       3. The process according to claim 1 wherein said polymerization catalyst comprises an (A) transition metal compound, (B) at least one compound selected from the group consisting of an (a) compound capable of reacting with said transition metal compound as the component (A) to form an ionic complex and a (b) oxygen atom-containing compound represented by the formula (I) or by the formula (II) ##STR13## wherein Z is a structure in which one or more groups represented by the formula ##STR14## are arranged in an arbitrary order in the number of arbitrary positive integers; R 1  to R 9  are each an alkyl group having 1 to 8 carbon atoms and may be the same as or different from each other; Y 1  and Y 3  are each a Group 13 metal of the Periodic Table and may be the same as or different from each other; and y 2  and y 4  are each a Group 14 metal of the Periodic Table and may be the same as or different from each other and a (C) alkyl group-containing metallic compound. 
     
     
       4. The process according to claim 2 wherein the transition metal compound as the component (A) is a titanium compound which has at least one ligand with conjugated π electrons. 
     
     
       5. The process according to claim 3 wherein the transition metal compound as the component (A) is a titanium compound which has at least one ligand with conjugated π electrons. 
     
     
       6. The process according to claim 2 Wherein the oxygen atom-containing compound as the component (B)-(b) is a reaction product of an organoaluminum compound and water. 
     
     
       7. The process according to claim 3 wherein the oxygen atom-containing compound as the component (B)-(b) is a reaction product of an organoaluminum compound and water. 
     
     
       8. The process according to claim 3 wherein the alkyl group-containing compound as the component (C) is an alkyl group-containing aluminum compound. 
     
     
       9. The process according to claim 1 wherein said styrenic monomer has a content of indene-based compounds of at most 30 ppm. 
     
     
       10. The process according to claim 1 wherein said styrenic monomer having a content of indene-based compounds of at most 50 ppm is produced by purifying a styrenic monomer containing indene-based compounds by means of at least one process selected from the group consisting of distillation and chromatography.